Search

Water plays a vital role in the life cycle of plants, participating in various critical biochemical reactions during both non‐photosynthetic and photosynthetic processes. Direct visualization of the metabolic activities of water in plants with high spatiotemporal resolution is essential to reveal the functional utilization of water. Here, stimulated Raman scattering (SRS) microscopy is applied to monitor the metabolic processes of deuterated water (D2O) in model plant Arabidopsis thaliana (A. thaliana). The work shows that in plants uptaking D2O/water solution, proton‐transfer from water to organic metabolites results in the formation of C‐D bonds in newly synthesized biomolecules (lipid, protein, and polysaccharides, etc.) that allow high‐resolution detection with SRS. Reversible metabolic pathways of oil‐starch conversion between seed germination and seed development processes are verified. Spatial heterogeneity of metabolic activities along the vertical axis of plants (root, stem, and tip meristem), as well as the radial distributions of secondary growth on the horizontal cross‐sections are quantified. Furthermore, metabolic flow of protons from plants to animals is visualized in aphids feeding on A. thaliana. Collectively, SRS microscopy has potential to trace a broad range of matter flows in plants, such as carbon storage and nutrition metabolism. [ABSTRACT FROM AUTHOR]

This study explored whether and how prohexadione calcium (Pro-Ca) regulated wheat tolerance to drought stress (DS). Findings displayed that DS had significant influence on antioxidant metabolism, water balance and the photosynthesis. DS significantly improved the activity level of enzymatic antioxidants superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX), the contents of non-enzymatic antioxidants ascorbic acid (AsA) and glutathione (GSH), electrolyte leakage (EL), malondialdehyde (MDA), and the contents of osmotic regulatory substances soluble protein (SP), soluble sugars (SS) and proline (Pro), compared with control. Whereas DS significantly reduced transpiration rate (Tr), stomatal conductance (gs) and relative water content (RWC), photosynthetic pigments chlorophyll and carotenoid contents, net photosynthetic rate (Pn), maximum photochemical efficiency of PSII (Fv/Fm), plant height and biomass. Compared to DS, Pro-Ca plus DS significantly promoted the antioxidant metabolism by improving the activity level of SOD, CAT, POD and APX and increasing AsA and GSH contents, which in turn reduced MDA content and EL. In addition, Pro-Ca plus DS significantly maintained water balance by promoting the accumulation of osmolytes SP, SS and Pro, which in turn increased RWC, Tr and gs. Pro-Ca plus DS also significantly promoted photosynthesis by increasing the contents of the above photosynthetic pigments, Pn and Fv/Fm, thereby promoting plant growth. These findings indicated that Pro-Ca was a potential agent to improve wheat tolerance under water deficit. [ABSTRACT FROM AUTHOR]

Introduction. Avoiding solid foods and liquids before surgery is a common practice in elective surgery in pediatric, however, there is a risk of dehydration.The objective was to assess the distribution of fluid across the water sectors of the body in children according to the duration of refusal of food and liquids before elective surgery.Materials and methods. A single-center prospective cohort study. 104 children were examined, the average age was 12.5 ± 3.7 years. Depending on the age, patients were divided into three groups: group I: 3–7 years old, group II: 7–12 years old and group III: 12–18 years old. In each group, taking into account the duration of preoperative refusal of food and fluid, there were two subgroups: subgroup I – less than 12 hours; subgroup II – more than 12 hours. The average fasting time was 13.3 ± 2.7 hours. The condition of the water sectors of the body was assessed 30 minutes before surgery, 30 minutes and 24 hours after surgery.Results. Before the operation, the distribution of fluid across the water sectors in groups I and II, depending on the duration of fasting, did not differ; in group III, when fasting for more than 12 hours, all indicators were significantly lower. 30 minutes and 24 hours after the intervention, an increase in the volume of total water and extracellular fluid was observed, however, significant changes were only in group III (p < 0.05). In group III, when fasting for more than 12 hours before surgery, lower systolic BP values were observed (p < 0.05).Conclusion. The duration of preoperative refusal of solid food and liquids in the range of 12–15 hours does not adversely affect the indicators of water metabolism and is not associated with arterial hypotension during the induction of anesthesia.

Introduction: Blood pressure (BP) regulation is a complex process involving several factors, among which water-sodium balance holds a prominent place. Arginin-vasopressin (AVP), a key player in water metabolism, has been evoked in hypertension development since the 1980s, but, to date, the matter is still controversial. Hyaluronic acid metabolism has been reported to be involved in renal water management, and AVP appears to increase hyaluronidase activity resulting in decreased high-molecular-weight hyaluronan content in the renal interstitium, facilitating water reabsorption in collecting ducts. Hence, our aim was to evaluate urinary hyaluronidase activity in response to an oral water load in hypertensive patients (HT, n=21) compared to normotensive subjects with (NT+, n=36) and without (NT-, n=29) a family history of hypertension, and to study its association with BP and AVP system activation, expressed by serum copeptin levels and urine Aquaporin 2 (AQP2)/creatinine ratio. Methods: Eighty-six Caucasian men were studied. Water load test consisted in oral administration of 15-20 ml of water/kg body weight over 40-45 min. BP, heart rate, serum copeptin, urine hyaluronidase activity and AQP2 were monitored for 4 hours. Results: In response to water drinking, BP raised in all groups with a peak at 20-40 min. Baseline levels of serum copeptin, urinary hyaluronidase activity and AQP2/creatinine ratio were similar among groups and all decreased after water load, reaching their nadir at 120 min and then gradually recovering to baseline values. Significantly, a blunted reduction in serum copeptin, urinary hyaluronidase activity and AQP2/creatinine ratio was observed in NT+ compared to NT-subjects. A strong positive correlation was also found between urinary hyaluronidase activity and AQP2/creatinine ratio, and, although limited to the NT- group, both parameters were positively associated with systolic BP. Discussion: Our results demonstrate for the first time the existence in men of a close association between urinary hyaluronidase activity and vasopressinergic system and suggest that NT+ subjects have a reduced ability to respond to water loading possibly contributing to the blood volume expansion involved in early-stage hypertension. Considering these data, AVP could play a central role in BP regulation by affecting water metabolism through both hyaluronidase activity and AQP2 channel expression. [ABSTRACT FROM AUTHOR]

Abstract Water plays a vital role in the life cycle of plants, participating in various critical biochemical reactions during both non‐photosynthetic and photosynthetic processes. Direct visualization of the metabolic activities of water in plants with high spatiotemporal resolution is essential to reveal the functional utilization of water. Here, stimulated Raman scattering (SRS) microscopy is applied to monitor the metabolic processes of deuterated water (D2O) in model plant Arabidopsis thaliana (A. thaliana). The work shows that in plants uptaking D2O/water solution, proton‐transfer from water to organic metabolites results in the formation of C‐D bonds in newly synthesized biomolecules (lipid, protein, and polysaccharides, etc.) that allow high‐resolution detection with SRS. Reversible metabolic pathways of oil‐starch conversion between seed germination and seed development processes are verified. Spatial heterogeneity of metabolic activities along the vertical axis of plants (root, stem, and tip meristem), as well as the radial distributions of secondary growth on the horizontal cross‐sections are quantified. Furthermore, metabolic flow of protons from plants to animals is visualized in aphids feeding on A. thaliana. Collectively, SRS microscopy has potential to trace a broad range of matter flows in plants, such as carbon storage and nutrition metabolism.

[ Objective ] This study aims to explore the protective mechanism of exogenous silicon on water metabolism and photosynthesis of Cucurbita pepo L. seedlings under salt stress , and to provide theoretical reference for salt resistance of C . pepo L.. [ Methods ] Using “ Hanlu 7042 ” C . pepo L. variety as the test material and hydroponic experiment , four treatments were set : Control , silicon treatment ( 0.3 mmol / L Na 2 SiO 3 · 9H 2 O ), salt stress ( 150 mmol / L NaCl ), salt stress+silicon treatment ( 0.3 mmol / L Na 2 SiO 3 · 9H 2 O+150 mmol / L NaCl ) . After 10 days of treatment , root morphology and activity , leaf water con- tent and water potential , photosynthetic parameters , chlorophyll content , chlorophyll fluorescence param- eters , and expression of aquaporin genes were determined. [ Results ] Salt stress inhibited the growth of C . pepo L. seedling roots , and decreased root activity , leaf water content , and leaf water potential and tran- spiration. Salt stress also affected the photosynthetic system , net photosynthetic rate , stomatal conduct- ance , chlorophyll content , and PSⅡ photochemical efficiency. Exogenous silicon improved the root mor- phology and activity of C . pepo L. seedlings under salt stress , also improved plant water status , and leaf water content , leaf water potential , and transpiration by promoting the expression of genes PIP1 ; 2 , PIP1 ; 3 , PIP1 ; 5 , PIP1 ; 7 , PIP2 ; 1 , PIP2 ; 4 , PIP2 ; 6 , and PIP2 ; 8 , PIP2 ; 9 and PIP2 ; 12 . The exogenous silicon also increased the stomatal conductance , chlorophyll content , net photosynthetic rate , PSⅡ maximum photochemical efficiency , PSⅡ actual photochemical efficiency , and photochemical quenching coefficient , decreased intercellular carbon dioxide concentration and non-photochemical quench- ing coefficient , enhanced the photosynthesis of seedlings under salt stress. [ Conclusion ] 0.3 mmol / L sili- con could improve the water metabolism and photosynthesis of C . pepo L. seedlings under salt stress , and thus enhance the ability of C . pepo L. seedlings to resist salt stress.

IntroductionBlood pressure (BP) regulation is a complex process involving several factors, among which water-sodium balance holds a prominent place. Arginin-vasopressin (AVP), a key player in water metabolism, has been evoked in hypertension development since the 1980s, but, to date, the matter is still controversial. Hyaluronic acid metabolism has been reported to be involved in renal water management, and AVP appears to increase hyaluronidase activity resulting in decreased high-molecular-weight hyaluronan content in the renal interstitium, facilitating water reabsorption in collecting ducts. Hence, our aim was to evaluate urinary hyaluronidase activity in response to an oral water load in hypertensive patients (HT, n=21) compared to normotensive subjects with (NT+, n=36) and without (NT-, n=29) a family history of hypertension, and to study its association with BP and AVP system activation, expressed by serum copeptin levels and urine Aquaporin 2 (AQP2)/creatinine ratio.MethodsEighty-six Caucasian men were studied. Water load test consisted in oral administration of 15–20 ml of water/kg body weight over 40–45 min. BP, heart rate, serum copeptin, urine hyaluronidase activity and AQP2 were monitored for 4 hours.ResultsIn response to water drinking, BP raised in all groups with a peak at 20–40 min. Baseline levels of serum copeptin, urinary hyaluronidase activity and AQP2/creatinine ratio were similar among groups and all decreased after water load, reaching their nadir at 120 min and then gradually recovering to baseline values. Significantly, a blunted reduction in serum copeptin, urinary hyaluronidase activity and AQP2/creatinine ratio was observed in NT+ compared to NT- subjects. A strong positive correlation was also found between urinary hyaluronidase activity and AQP2/creatinine ratio, and, although limited to the NT- group, both parameters were positively associated with systolic BP.DiscussionOur results demonstrate for the first time the existence in men of a close association between urinary hyaluronidase activity and vasopressinergic system and suggest that NT+ subjects have a reduced ability to respond to water loading possibly contributing to the blood volume expansion involved in early-stage hypertension. Considering these data, AVP could play a central role in BP regulation by affecting water metabolism through both hyaluronidase activity and AQP2 channel expression.

Study region: The Lijiang River Basin in southwest China. Study focus: This research focuses on the structure, function, and evolution of the water metabolic system. It quantifies multiple water metabolic processes involve in water cycle, considering natural and social influences. Furthermore, an integrated water metabolism network system is established, and the ecological network analysis is introduced to quantitatively simulate the water circulation in metabolic processes and analyze the interaction between metabolic components in the Lijiang River Basin during 2010 to 2020. New hydrological insights for the region: The results contribute to a deeper understanding of the nature, state, and stability of water metabolism. The water metabolic system in the basin is balanced, with a moderate robustness and a high efficiency. The structure of the water metabolism is unchanged, with little fluctuation of the flow transmission, revealing the development of metabolic structure in the Lijiang River Basin. The surface water compartment (more than 80% of the total) contributes most significantly to the water metabolic processes, with abundant natural inflow. Water consumption is mainly driven by the agricultural irrigation compartment. The relationships among pairwise compartments are mutualistic and synergistic, indicating a healthy metabolic process. Exploitation and being exploited relationships are the dominant types. These insights reveal how water metabolism is quantified, and the water metabolic structure and relationships can be further optimized by improving the water efficiency.

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals. [ABSTRACT FROM AUTHOR]

The karst carbon sink caused by rock outcrops results in enrichment of the bicarbonate in soil, affecting the physiological process of plants in an all-round way. Water is the basis of plant growth and metabolic activities. In heterogeneous rock outcrop habitats, the impact of bicarbonate enrichment on the intracellular water metabolism of plant leaf is still unclear, which needs to be revealed. In this paper, the Lonicera japonica and Parthenocissus quinquefolia plants were selected as experimental materials, and electrophysiological indices were used to study their water holding, transfer and use efficiency under three simulated rock outcrop habitats, i.e., rock/soil ratio as 1, 1/4 and 0. By synchronously determining and analyzing the leaf water content, photosynthetic and chlorophyll fluorescence parameters, the response characteristics of water metabolism within leaf cells to the heterogeneous rock outcrop habitats were revealed. The results showed that the soil bicarbonate content in rock outcrop habitats increased with increasing rock/soil ratio. Under the treatment of a higher concentration of bicarbonate, the leaf intra- and intercellular water acquisition and transfer efficiency as well as the photosynthetic utilization capacity of P. quinquefolia decreased, the leaf water content was lower, and those plants had low bicarbonate utilization efficiency, which greatly weakened their drought resistance. However, the Lonicera japonica had a high bicarbonate use capacity when facing the enrichment of bicarbonate within cells, the above-mentioned capacity could significantly improve the water status of the leaves, and the water content and intracellular water-holding capacity of plant leaves in large rock outcrop habitats were significantly better than in non-rock outcrop habitats. In addition, the higher intracellular water-holding capacity was likely to maintain the stability of the intra- and intercellular water environment, thus ensuring the full development of its photosynthetic metabolic capacity, and the stable intracellular water-use efficiency also made itself more vigorous under karstic drought. Taken together, the results suggested that the water metabolic traits of Lonicera japonica made it more adaptable to karst environments. [ABSTRACT FROM AUTHOR]

Aquaporins (AQPs) are a family of transmembrane proteins expressed in various organ systems. Many studies have shown that the abnormal expression of AQPs is associated with gastrointestinal, skin, liver, kidneys, edema, cancer, and other diseases. The majority of AQPs are expressed in the digestive system and have important implications for the physiopathology of the gastrointestinal tract as well as other tissues and organs. AQP regulators can prevent and treat most gastrointestinal-related diseases, such as colorectal cancer, gastric ulcer, and gastric cancer. Although recent studies have proposed clinically relevant AQPtargeted therapies, such as the development of AQP inhibitors, clinical trials are still lacking and there are many difficulties. Traditional Chinese medicine (TCM) has been used in China for thousands of years to prevent, treat and diagnose diseases, and is under the guidance of Chinese medicine (CM) theory. Herein, we review the latest research on the regulation of AQPs by TCMs and their active components, including Rhei Radix et Rhizoma, Atractylodis macrocephalae Rhizoma, Salviae miltiorrhizae Radix et Rhizoma, Poria, Astragali radix, and another 26 TCMs, as well as active components, which include the active components include anthraquinones, saponins, polysaccharides, and flavonoid glycosides. Through our review and discussion of numerous studies, we attempt to explore the regulatory effects of TCMs and their active components on AQP expression in the corresponding parts of the body in terms of the Triple Energizer concept in Chinese medicine defined as "upper energizer, middle energizer, and lower energizer,"so as to offer unique opportunities for the development of AQPrelated therapeutic drugs for digestive system diseases. [ABSTRACT FROM AUTHOR]

The activation of the Ca 2+ -channel Orai1 via the physiological activator stromal interaction molecule 1 (STIM1) requires structural rearrangements within the entire channel complex involving a series of gating checkpoints. Focusing on the gating mechanism operating along the peripheral transmembrane domain (TM) 3/TM4-interface, we report here that some charged substitutions close to the center of TM3 or TM4 lead to constitutively active Orai1 variants triggering nuclear factor of activated T-cell (NFAT) translocation into the nucleus. Molecular dynamics simulations unveil that this gain-of-function correlates with enhanced hydration at peripheral TM-interfaces, leading to increased local structural flexibility of the channel periphery and global conformational changes permitting pore opening. Our findings indicate that efficient dehydration of the peripheral TM-interfaces driven by the hydrophobic effect is critical for maintaining the closed state of Orai1. We conclude that a charge close to the center of TM3 or TM4 facilitates concomitant hydration and widening of peripheral TM interfaces to trigger constitutive Orai1 pore opening to a level comparable to or exceeding that of native activated Orai1., Competing Interests: Competing interests The authors declare no competing interests. Consent to publish All authors have read and approved its submission to this journal., (© 2024. The Author(s).)

The co-occurrence of drought and heat significantly hampers plant productivity. Although their impacts are well studied, these studies have been based on the effects of individual stressors rather than their combined influence. Okra is crucial for food and nutritional security and livelihoods in many regions, yet it remains under-researched and unimproved. Okra has been proven to be sensitive to both drought and heat stress. This study employed a cost-effective phenotyping method to assess key traits characterising the diversity of okra morphophysiological responses to independent and interactive heat-drought stresses. This study aimed to understand okra responses to stress, identify stress-resilient traits, and characterise okra genotypes. We also addressed the need to examine interactive stress effects, which mirror real-world scenarios more accurately than single-stress studies. Sixty-three okra genotypes were subjected to heat, drought, or concurrent heat-drought stress at the seedling stage in improvised climate-controlled chambers. The germplasm exhibited significant variations in response to the various stresses. The broad-sense heritability was high (> 0.60) for traits such as chlorophyll content, plant biomass, performance indices, electrolyte leakage, and total leaf area. Drought stress alone had a more pronounced effect than heat stress alone, and the adverse impact was worsened under combined heat and drought stress. The interactive impact of drought and heat was more likely additive than antagonistic or synergistic. A positive and strong relationship was observed between photosynthetic efficiency parameters such as the Fv/Fm ratio, chlorophyll content, relative water index, and biomass parameters such as dry shoot weight. The 63 okra genotypes were classified into three distinct clusters, suggesting potential for future breeding efforts. Okra genotype considered to be tolerant or climate resilient (such as GH170, V1060831, GH174, V1060874, and GH106) to drought and heat, maintained enhanced photosynthetic efficiency and high internal water potential, possibly reducing osmotic and oxidative damage. This study revealed some mechanisms underlying the adaptation of okra genotypes to independent and combined heat and drought stress. The results provide a basis for breeding efforts to develop climate-resilient okra varieties., Competing Interests: Declarations Competing interests The authors declare no competing interests. Compliance and consents The experiment complied with relevant institutional, national, and international guidelines and legislation. The Council of Scientific and Industrial Research—Crop Research Institute (CSIR-CRI) of Ghana and the World Vegetable Center Genebank supplied the okra germplasm. They granted permission to use the genetic materials in the study., (© 2024. The Author(s).)

We investigated the renal function of the brackish water clam, Ruditapes philippinarum, employing magnetic resonance imaging (MRI). The R. philippinarum kidney consists of two renal tubules, a glandular (GT) and a saccular (ST) tubule. After exposure to seawater containing manganese ion (Mn2+) at 20°C, the intensity of the T1-weighted MRI and longitudinal relaxation rates (1/T1=R1) of the kidney were increased. In the ST, haemolymph containing Mn2+ entered directly from the auricle, and the Mn2+ concentration ([Mn2+]) increased in the initial part of the ST. Thereafter, [Mn2+] was almost constant until the posterior end of the kidney. The GT received haemolymph from the pedal sinus via the visceral sinus. The GT runs parallel inside the ST, and [Mn2+] increased progressively until it merged with the ST. In a range of seawater with [Mn2+] from 1 to 30 µmol l-1, the [Mn2+] increased 12-fold in the posterior part of the ST, compared with the ambient [Mn2+]. Based on these results, the epithelium of the initial part of the ST reabsorbs water from luminal fluid, building up a higher osmotic pressure. Using this osmotic gradient, hypertonic water is reabsorbed via the epithelium of the GT to the ST, and then transferred to the haemolymph via the epithelium of the ST. Excess water is excreted as urine. This model was supported by the increases in [Mn2+] in the ST when the clams were exposed to seawater containing Mn2+ at salinity from 26.0 to 36.0‰, showing that the parallel-current system works in hypotonic seawater., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Environmental change requires more crop production per water use to meet the rising global food demands. However, improving crop intrinsic water use efficiency (iWUE) usually comes at the expense of carbon assimilation. Sorghum is a key crop in many vulnerable agricultural systems with higher tolerance to water stress (WS) than most widely planted crops. To investigate physiological controls on iWUE and its inheritance in sorghum, we screened 89 genotypes selected based on inherited haplotypes from an elite line or five exotics lines, containing a mix of geographical origins and dry versus milder climates, which included different aquaporin (AQP) alleles. We found significant variation among key highly heritable gas exchange and hydraulic traits, with some being significantly affected by variation in haplotypes among parental lines. Plants with a higher proportion of the non-stomatal component of iWUE still maintained iWUE under WS by maintaining photosynthetic capacity, independently of reduction in leaf hydraulic conductance. Haplotypes associated with two AQPs (SbPIP1.1 and SbTIP3.2) influenced iWUE and related traits. These findings expand the range of traits that bridge the trade-off between iWUE and productivity in C4 crops, and provide possible genetic regions that can be targeted for breeding., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

In this study, we assessed 43 accessions of sorghum from 16 countries across three continents. Our objective was to identify stomatal and photosynthetic traits that could be exploited in breeding programmes to increase photosynthesis without increasing water use under dynamic light environments. Under field conditions, sorghum crops often have limited water availability and are exposed to rapidly fluctuating light intensities, which influences both photosynthesis and stomatal behaviour. Our results highlight a tight coupling between photosynthetic rate (A) and stomatal conductance (gs) even under dynamic light conditions that results in steady intrinsic water use efficiency (Wi). This was mainly due to rapid stomatal responses, with the majority of sorghum accessions responding within ≤5 min. The maintenance of the ratio of the concentration of CO2 inside the leaf (Ci) and the surrounding atmospheric concentration (Ca) over a large range of accessions suggests high stomatal sensitivity to changes in Ci, that could underlie the rapid gs responses and extremely close relationship between A and gs under both dynamic and steady-state conditions. Therefore, sorghum represents a prime candidate for uncovering the elusive mechanisms that coordinate A and gs, and such information could be used to design crops with high A without incurring significant water losses and eroding Wi., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Ethylene, a plant hormone that significantly influences both plant growth and response to stress, plays a well-established role in stress signaling. However, its impact on stomatal opening and closure during dehydration and rehydration remains relatively unexplored and is still debated. Exogenous ethylene has been proven to induce stomatal closure through a series of signaling pathways, including the accumulation of reactive oxygen species, subsequent synthesis of nitric oxide and hydrogen sulfide, and SLOW ANION CHANNEL-ASSOCIATED 1 activation. Thus, it has been suggested that ethylene might function to induce stomatal closure synergistically with abscisic acid (ABA). Furthermore, it has also been shown that increased ethylene can inhibit ABA- and jasmonic acid-induced stomatal closure, thus hindering drought-induced closure during dehydration. Simultaneously, other stresses, such as chilling, ozone pollution, and K+ deficiency, inhibit drought- and ABA-induced stomatal closure in an ethylene synthesis-dependent manner. However, ethylene has been shown to take on an opposing role during rehydration, preventing stomatal opening in the absence of ABA through its own signaling pathway. These findings offer novel insights into the function of ethylene in stomatal regulation during dehydration and rehydration, giving a better understanding of the mechanisms underlying ethylene-induced stomatal movement in seed plants., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The ratio of net CO2 uptake (Anet) and stomatal conductance (gs) is an intrinsic measurement of leaf water use efficiency (WUEi); however, its measurement can be challenging for large phenotypic screens. Measurements of the leaf carbon isotope composition (δ13Cleaf) may be a scalable tool to approximate WUEi for screening because it in part reflects the competing influences of Anet and gs on the CO2 partial pressure (pCO2) inside the leaf over time. However, in C4 photosynthesis, the CO2-concentrating mechanism complicates the relationship between δ13Cleaf and WUEi. Despite this complicated relationship, several studies have shown genetic variation in δ13Cleaf across C4 plants. Yet there has not been a clear demonstration of if Anet or gs are the causal mechanisms controlling WUEi and δ13Cleaf. Our approach was to characterize leaf photosynthetic traits of two Zea mays recombinant inbred lines (Z007E0067 and Z007E0150) which consistently differ for δ13Cleaf even though they have minimal confounding genetic differences. We demonstrate that these two genotypes contrasted in WUEi driven by differences in the speed of stomatal responses to changes in pCO2 and light that lead to unproductive leaf water loss. These findings provide support that differences in δ13Cleaf in closely related genotypes do reflect greater WUEi and further suggest that differences in stomatal kinetic response to changing environmental conditions is a key target to improve WUEi., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Stomata regulate CO2 and water vapor exchange between leaves and the atmosphere. Stomata are a target for engineering to improve crop intrinsic water use efficiency (iWUE). One example is by expressing genes that lower stomatal density (SD) and reduce stomatal conductance (gsw). However, the quantitative relationship between reduced SD, gsw, and the mechanisms underlying it is poorly understood. We addressed this knowledge gap using low-SD sugarcane (Saccharum spp. hybrid) as a case study alongside a meta-analysis of data from 10 species. Transgenic expression of EPIDERMAL PATTERNING FACTOR 2 from Sorghum bicolor (SbEPF2) in sugarcane reduced SD by 26-38% but did not affect gsw compared with the wild type. Further, no changes occurred in stomatal complex size or proxies for photosynthetic capacity. Measurements of gas exchange at low CO2 concentrations that promote complete stomatal opening to normalize aperture size between genotypes were combined with modeling of maximum gsw from anatomical data. These data suggest that increased stomatal aperture is the only possible explanation for maintaining gsw when SD is reduced. Meta-analysis across C3 dicots, C3 monocots, and C4 monocots revealed that engineered reductions in SD are strongly correlated with lower gsw (r2=0.60-0.98), but this response is damped relative to the change in anatomy., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Enhancing crop water use efficiency (WUE) is a key target trait for climatic resilience and expanding cultivation on marginal lands. Engineering lower stomatal density to reduce stomatal conductance (gs) has improved WUE in multiple C3 crop species. However, reducing gs in C3 species often reduces photosynthetic carbon gain. A different response is expected in C4 plants because they possess specialized anatomy and biochemistry which concentrates CO2 at the site of fixation. This modifies the relationship of photosynthesis (AN) with intracellular CO2 concentration (ci), such that photosynthesis is CO2 saturated and reductions in gs are unlikely to limit AN. To test this hypothesis, genetic strategies were investigated to reduce stomatal density in the C4 crop sorghum. Constitutive expression of a synthetic epidermal patterning factor (EPF) transgenic allele in sorghum led to reduced stomatal densities, reduced gs, reduced plant water use, and avoidance of stress during a period of water deprivation. In addition, moderate reduction in stomatal density did not increase stomatal limitation to AN. However, these positive outcomes were associated with negative pleiotropic effects on reproductive development and photosynthetic capacity. Avoiding pleiotropy by targeting expression of the transgene to specific tissues could provide a pathway to improved agronomic outcomes., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Plasma-activated water (PAW) contains multiple active species that alter the structure of myofibrillar protein (MP) to enhance their gel properties. This work investigated the impact of PAW on the oxidation of cysteine in MP by label-free quantitative proteomics. PAW treatment caused the oxidation of 8241 cysteine sites on 2815 proteins, and structural proteins such as nebulin, myosin XVIIIB, myosin XVIIIA, and myosin heavy chain were susceptible to oxidation by PAW. Bioinformatics analysis, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, subcellular localization, and STRING analysis, indicated that these proteins with differential oxidation sites were mainly derived from the cytoplasm and membrane, and were involved in multiple GO terms and KEGG pathways. This is one of the first reports of the redox proteomic changes induced by PAW treatment, and the results are useful for understanding the possible mechanism of PAW-induced oxidation of MP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The impact of climate change on agricultural production is apparent due to declining irrigation water availability vis-à-vis rising drought stress, particularly affecting summer crops. Growing evidence suggests that zinc (Zn) supplementation may serve as a potential drought stress management strategy in agriculture. Field studies were conducted using soybean (Glycine max var. Saba) as a model crop to test whether foliar application of zinc oxide nanoparticles (ZnO-NPs) or conventional Zn fertilizer (ZnSO 4 ) would mitigate drought-related water stress and improve soybean yield. Each fertilizer was foliar applied twice at a two-week interval during the flowering stage. Experiments were concurrently conducted under non-drought conditions (70% field capacity) for comparison. Results showed drought significantly reduced relative water content, chlorophyll-a, and chlorophyll-b in untreated control plants by 35.7%, 47.7%, and 41.4%, respectively, compared to non-drought conditions (p < 0.05). Under drought conditions, ZnO-NPs (200 mg Zn/L) led to 33.1% and 20.7% increase in chlorophyll-a and chlorophyll-b levels, respectively, compared to ZnSO 4 at 400 mg Zn/L. Likewise, catalase, peroxidase and superoxide dismutase activities increased by 62.6%, 39.5% and 28.5%, respectively, with ZnO-NPs (200 mg Zn/L) under drought compared to non-drought conditions. Proline was significantly increased under drought but was remarkably suppressed (~ 54% lower) with ZnO-NPs (200 mg Zn/L) treatment. More importantly, the highest seed yield was observed with ZnO-NPs (200 mg Zn/L) treatment under drought (39% higher than untreated control) and non-drought (79.4% higher than control) conditions. Overall, the findings suggest that ZnO-NPs could promote seed yield in soybean under drought stress via increased antioxidant activities, increased relative water content, decreased stress-related proline content, and increased photosynthetic pigments. It is recommended that foliar application of 200 mg Zn/L as ZnO-NPs could serve as an effective drought stress management strategy to improve soybean yield., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

The mass transport effect of aqueous micelles on antioxidants and oxidation products in emulsions may alter the rate, degree, and pathway of lipid oxidation. In this study, the dynamic mass transport of oxidation products and endogenous tocopherol during storage at different micelle concentrations was monitored by UV-vis spectrophotometry and high-performance liquid chromatography. Furthermore, the microlocalization of tocopherol in micelles was investigated using 1 H nuclear magnetic resonance and nuclear Overhauser effect spectroscopy, fluorescence measurements, and molecular dynamics simulation. It was demonstrated that high-concentration micelles enhanced the emulsion stability by promoting the mass transport of hydroperoxides and endogenous antioxidants. The enhancement of micelles was a superposition effect of concentration, interaction sites, and binding force between tocopherols and Tween 20 molecules. Tween 20 concentration-induced favorable changes of microlocalization of tocopherol and dynamic mass transport demonstrated a new integrated perspective to control lipid oxidation.

Background and Aims: Leaf elongation is vital for productivity of Poaceae species, influenced by atmospheric CO2 concentration ([CO2]) and climate-induced water availability changes. Although [CO2] mitigates the effects of drought on reducing transpiration per unit leaf area, it also increases total leaf area and water use. These complex interactions associated with leaf growth pose challenges in anticipating climate change effects. This study aims to assess [CO2] effects on leaf growth response to drought in perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea) and wheat (Triticum aestivum)., Methods: Plants were cultivated in growth chambers with [CO2] at 200 or 800 ppm. At leaf six to seven unfolding, half of the plants were subjected to severe drought treatment. Leaf elongation rate (LER) was measured daily, whereas plant transpiration was continuously recorded gravimetrically. Additionally, water-soluble carbohydrate (WSC) content along with water and osmotic potentials in the leaf growing zone were measured at drought onset, mid-drought and leaf growth cessation., Key Results: Elevated [CO2] mitigated drought impacts on LER and delayed growth cessation across species. A positive correlation between LER and soil relative water content (SRWC) was observed. At the same SRWC, perennial grasses exhibited a higher LER with elevated [CO2], probably due to enhanced stomatal regulation. Despite stomatal closure and WSC accumulation, CO2 did not influence nighttime water potential or osmotic potential. The marked increase in leaf area across species resulted in similar (wheat and tall fescue) or higher (ryegrass) total water use by the end of the experiment, under both watered and unwatered conditions., Conclusions: Elevated [CO2] mitigates the adverse effects of drought on leaf elongation in three Poaceae species, due to its impact on plant transpiration. Overall, these findings provide valuable insights into CO2 and drought interactions that may help anticipate plant responses to climate change., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: In epiphytic bromeliads, the roots were previously considered to be poorly functional organs in the processes of absorption and metabolization of water and nutrients, while the leaves were considered to always act as protagonists in both functions. More recent discoveries have been changing this old view of the root system., Scope: In this review, we address previous ideas regarding the function performed by the roots of epiphytic bromeliads (mere holdfast structures with low physiological activity) and the importance of a reduced or lack of a root system for the emergence of epiphytism. We present indirect and direct evidence that contradicts this older hypothesis. Furthermore, the importance of the root absorptive function mainly for juvenile tankless epiphytic bromeliads and the characteristics of the root absorption process of adult epiphytic tank bromeliads are discussed thoroughly from a physiological perspective. Finally, some factors (species, substrate, environmental conditions) that influence the absorptive capability of the roots of epiphytic tank bromeliads are also be considered, highlighting the importance that the absorptive role of the roots has for the plasticity of bromeliads that live on trees, which is an environment characterized by intermittent availability of water and nutrients., Conclusions: The roots of tank-forming epiphytic bromeliads play important roles in the absorption and metabolization of nutrients and water. The importance of roots is greatest for juvenile tankless bromeliads since the root is the main absorptive organ. In larger plants with a tank, although the leaves become the protagonists in the resource acquisition process, the roots complement the absorptive function of the leaf trichomes, resulting in improved growth of these bromeliad. The physiological and biochemical properties of the processes of absorption and distribution of resources in the tissues appear to differ between absorption by trichomes and roots., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Waterlogging stands as a common environmental challenge, significantly affecting plant growth, yield, and, in severe cases, survival. In response to waterlogging stress, plants exhibit a series of intricate physiologic, metabolic, and morphologic adaptations. Notably, the gaseous phytohormone ethylene is rapidly accumulated in the plant submerged tissues, assuming an important regulatory factor in plant-waterlogging tolerance. In this review, we summarize recent advances in research on the mechanisms of ethylene in the regulation of plant responses to waterlogging stress. Recent advances found that both ethylene biosynthesis and signal transduction make indispensable contributions to modulating plant adaptation mechanisms to waterlogged condition. Ethylene was also discovered to play an important role in plant physiologic metabolic responses to waterlogging stress, including the energy mechanism, morphologic adaptation, ROS regulation and interactions with other phytohormones. The comprehensive exploration of ethylene and its associated genes provides valuable insights into the precise strategies to leverage ethylene metabolism for enhancing plant resistance to waterlogging stress., Competing Interests: Declarations Competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The objective of this study was to evaluate the effects of different concentrations of hydrogen-rich water (HRW) on in vitro rumen fermentation characteristics and the dynamics of bacterial communities. The experiment included four treatment groups: a control (CON) and hydrogen-rich water (HRW) at 200, 400, and 800 ppb. Each group was analyzed at 12-hour (h) and 48-hour (h) time points with five replicates, totaling 40 samples. The experimental results highlighted the HRW 800ppb group as the top production in terms of gas production and CH 4 content. In contrast, the HRW 200ppb group exhibited significantly lower methane levels at both 12 h and 48 h (P < 0.05). Regarding rumen fermentation, the HRW 400ppb group significantly increased the levels of ammonia nitrogen (NH 3 -N) and microbial crude protein (MCP) at 12 h fermentation, but reduced the dry matter degradation rate (P < 0.05). After 48 h, the HRW 400ppb group had highest MCP content (P < 0.05), but no significant differences in NH 3 -N and dry matter degradation rate compared with the CON group (P > 0.05). Although HRW did not significantly benefit the synthesis of total volatile fatty acids (TVFA) and individual VFA, the HRW 800ppb group significantly increased the ratio of acetate to propionate (P < 0.05). Based on CH 4 emissions and MCP synthesis, we selected the HRW 400ppb group for subsequent bacterial community analysis. Bacterial community analysis showed that at 12 h, compared with the CON group, the Bacterial community analysis revealed that the HRW 400ppb group had significant increases in the Simpson index, Firmicutes, Streptococcus, Schwartzia, Prevotellaceae&#95;YAB2003&#95;group, and Oribacterium, and decreases in Prevotella, Ruminobacter, Succinivibrio, unclassified&#95;Succinivibrionaceae, and Prevotellaceae&#95;UCG-003 (P < 0.05). At 48 h, the Prevotellaceae&#95;YAB2003&#95;group and Oribacterium abundances continued to rise significantly, while Rikenellaceae&#95;RC9&#95;gut&#95;group and Succiniclasticum abundances fell in the HRW 400ppb group (P < 0.05). Correlation analysis indicated a negative link between CH 4 and Streptococcus, and a positive correlation between the abundance of Rikenellaceae&#95;RC9&#95;gut&#95;group and CH 4 . Collectively, these results indicate that HRW can modulate rumen fermentation and microbial community structure to reduce methane emissions without significantly affecting VFA synthesis, highlighting its potential as drinking water for enhancing ruminant nutrition and mitigating the environmental impact of livestock farming., Competing Interests: Declaration Ethics approval and consent to participate This experiment was approved by the Committee for the Care and Use of Experimental Animals at Jiangxi Agricultural University (JXAULL-2021-10). Consent for publication Not applicable. Competing interests The authors declare no competing interests. Ethics approval Animal care and experimental procedures were approved by the Animal Care Committee of Jiangxi Agricultural University (Nanchang, China), and were under the university’s guidelines for animal research. Clinical trial number Animal care and experimental procedures were approved by the Committee for the Care and Use of Experimental Animals at Jiangxi Agricultural University (JXAULL-2021-10)., (© 2024. The Author(s).)

Background: Accurate leaf water potential (Ψ w ) determination is crucial in studying plant responses to water deficit. After excision, water potential decreases, even under low evaporative demand conditions, which has been recently attributed to the equilibration of pre-excision Ψ w gradients across the leaf. We assessed the influence of potential re-equilibration on water potential determination by monitoring leaf Ψ w and relative water content decline after excision using different storage methods., Results: Even though leaf Ψ w declined during storage under low evaporative demand conditions, this was strongly reduced when covering the leaf with a hydrophobic layer (vaseline) and explained by changes in relative water content. However, residual water loss was variable between species, possibly related to morpho-physiological leaf traits. Provided water loss was minimized during storage, pre-excision leaf transpiration rate did not affect to the magnitude of leaf Ψ w decline after excision, confirming that transpiration-driven Ψ w gradients have no effect on leaf Ψ w determination., Conclusions: Disequilibrium in water potentials across a transpiring leaf upon excision is dissipated very quickly, well within the elapsed time between excision and pressurization, therefore, not resulting in overestimation of leaf Ψ w measured immediately after excision. When leaf storage is required, the effectiveness of a storage under low evaporative demand varied among species. Covering with a hydrophobic layer is an acceptable alternative., (© 2024. The Author(s).)

Stomata respond slowly to changes in light when compared with photosynthesis, undermining plant water-use efficiency (WUE). We know much about stomatal mechanics, yet efforts to accelerate stomatal responsiveness have been limited despite the breadth of potential targets for manipulation. Here, we use mechanistic modeling to establish a hierarchy of putative targets affecting stomatal kinetics. Counterintuitively, modeling predicted that overexpressing plasma membrane H + -ATPases could speed stomata and enhance WUE under fluctuating light, even though overexpressed H + -ATPases is known to promote stomatal opening and reduce WUE in the steady state. Experiments validated the prediction, implicating an unexpected role of the H + -ATPases in improving WUE under fluctuating light. It suggests that H + -ATPases have a dual function, acting as a facilitator of carbon assimilation and water use, depending on the light conditions. These findings highlight the importance of integrating in silico modeling with experiments in future efforts toward enhancing stomatal function.

Brain water homeostasis not only provides a physical protection, but also determines the diffusion of chemical molecules key for information processing and metabolic stability. As a major type of glia in brain parenchyma, astrocytes are the dominant cell type expressing aquaporin water channel. How astrocyte aquaporin contributes to brain water homeostasis in basal physiology remains to be understood. We report that astrocyte aquaporin 4 (AQP4) mediates a tonic water efflux in basal conditions. Acute inhibition of astrocyte AQP4 leads to intracellular water accumulation as optically resolved by fluorescence-translated imaging in acute brain slices, and in vivo by fiber photometry in mobile mice. We then show that aquaporin-mediated constant water efflux maintains astrocyte volume and osmotic equilibrium, astrocyte and neuron Ca 2+ signaling, and extracellular space remodeling during optogenetically induced cortical spreading depression. Using diffusion-weighted magnetic resonance imaging (DW-MRI), we observed that in vivo inhibition of AQP4 water efflux heterogeneously disturbs brain water homeostasis in a region-dependent manner. Our data suggest that astrocyte aquaporin, though bidirectional in nature, mediates a tonic water outflow to sustain cellular and environmental equilibrium in brain parenchyma., Competing Interests: CP, YK, AD, BL, CM, CF, AC, VV, TT, BC, DL No competing interests declared, (© 2024, Pham et al.)

Ex vivo studies of the brain are often employed as experimental systems in neuroscience. In general, brains for ex vivo MRI studies are usually fixed with paraformaldehyde to preserve molecular structure and prevent tissue destruction during long-term storage. As a result, fixing brain tissue causes microstructural changes and a decrease in brain volume. Therefore, the purpose of this study was to investigate the regional effect of brain volume and microstructural changes on the restricted diffusion of water molecules in the common marmoset brain using in vivo and ex vivo brains from the same individual. We used 9.4T magnetic resonance imaging and also compared the T2-weighted images and diffusion-weighted imaging (DWI) data between in vivo and ex vivo brains to investigate changes in brain volume and diffusion of water molecules in 12 common marmosets. We compared fractional anisotropy, mean diffusivity, AD (axial diffusivity), and radial diffusivity values in white matter and gray matter between in vivo and ex vivo brains. We observed that AD showed the strongest correlation with regional volume changes in gray matter. The results showed a strong correlation between AD and changes in brain volume. By comparing the in vivo and ex vivo brains of the same individual, we identified significant correlations between the local effects of perfusion fixation on microstructural and volumetric changes of the brain and alterations in the restricted diffusion of water molecules within the brain. These findings provide valuable insights into the complex relationships between tissue fixation, brain structure, and water diffusion properties in the marmoset brain., (© 2024. The Author(s).)

The key to restoring arid and semi-arid ecosystems is maintaining soil water and organic carbon contents. Alfalfa ( Medicago sativa L.) is a high-yield perennial forage crop and performs ecological functions as a drought-resistance leguminous herb. It has been widely planted for reconstruction of degraded soils in the Loess Plateau in northwestern China, but long-term planting may affect soil carbon-water coupling and lead to crop yield reduction. To maximize the benefits of reconstructed grassland, this study explored the couplings of soil water, organic carbon, and alfalfa productivity along a reconstruction chronosequence in a semi-arid area of the Loess Plateau. Space-for-time substitution approach was used to select different-aged stands of reconstructed grassland (1, 5, 7, 10, 15, 20, 30 years old). Alfalfa above-ground biomass (AGB), soil water storage (SWS), organic carbon storage (SOCS), and carbon-water coupling coordination degree ( D ) were measured in the 0-100 cm soil profile. Alfalfa AGB reached a peak in the 7th year, and the degradation began in the 10th year. Both SWS and SOCS varied nonlinearly with stand age. The greatest loss of SWS occurred in the 15th year (80-100 cm depth), whereas the largest increase of SOCS occurred in the 30th year (0-20 cm depth). There was a negative feedback relationship between AGB and SWS over the 30-year study period (Pearson r = -0.835, P = 0.098). AGB and SOCS initially showed a trade-off within the first 10 years (Pearson r = -0.7431, P = 0.2569), in contrast to their positive feedback in the 20-30th years (Pearson r = 0.9978, P = 0.0421). A decoupling between SWS and SOCS ( D < 0.6) was observed after 12 years of alfalfa planting. For agricultural production, a greater supply of water and organic fertilizer is required from the 7th year of alfalfa planting, and reseeding may be needed around the 10th year to prolong the life of alfalfa community. Alfalfa should be planted for no more than 12 consecutive years in the study area for ecological protection., Competing Interests: The authors declare there are no competing interests., (©2024 Ma et al.)

Desert shrubs play a crucial role in controlling desertification and promoting revegetation, but drought often hinders their growth. Investigating the hydraulic strategies of desert shrubs is important in order to understand their drought adaptation and predict future dynamics under climate change. In this study, we measured the hydraulic-related characteristics of roots, stems and leaves in 19 desert shrub species from northern China. We aimed to explore the hydraulic coordination and segmentation between different plant organs. The results were as follows: (i) specific root length was positively correlated with the water potential inducing a 50% loss in stem hydraulic conductivity (P50stem) and negatively correlated with stem hydraulic safety margin. This suggested that water uptake efficiency of the fine roots was traded off with stem embolism resistance and hydraulic safety. (ii) The water potential inducing a 50% loss in leaf hydraulic conductance was significantly less negative than P50stem, and fine root turgor loss point was significantly less negative than P50stem, indicating a hydraulic segmentation between the main stem and terminal organs. (iii) The most negative leaf turgor loss point indicated that leaf wilting occurred after substantial leaf and stem embolism. The high desiccation resistance of the leaves may serve as an important physiological mechanism to increase carbon gain in a relatively brief growth period. In summary, this study elucidated the hydraulic strategies employed by desert shrubs from a whole-plant perspective., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Unravelling the complexities of transpiration can be assisted by understanding the oxygen isotope composition of transpired water vapour (δE). It is often assumed that δE is at steady state, thereby mirroring the oxygen isotope composition of source water (δsource), but this assumption has never been tested at the whole-tree scale. This study utilized the unique infrastructure of 12 whole-tree chambers enclosing Eucalyptus parramattensis E.C.Hall trees to measure δE along with concurrent temperature and gas exchange data. Six chambers tracked ambient air temperature and six were exposed to an ambient +3 °C warming treatment. Day time means for δE were within 1.2‰ of δsource (-3.3‰) but varied considerably throughout the day. Our observations show that E. parramattensis trees are seldom transpiring at isotopic steady state over a diel period, but transpiration approaches source water isotopic composition over longer time periods., (© The Author(s) 2024. Published by Oxford University Press.)

Water-use efficiency (WUE) is affected by multiple leaf traits, including stomatal morphology. However, the impact of stomatal morphology on WUE across different ontogenetic stages of tree species is not well-documented. Here, we investigated the relationship between stomatal morphology, intrinsic water-use efficiency (iWUE) and leaf carbon isotope ratio (δ 13 C). We sampled 190 individuals, including juvenile and mature trees belonging to 18 temperate broadleaved tree species and 9 genera. We measured guard cell length (GCL), stomatal density (SD), specific leaf area (SLA), iWUE and bulk leaf δ 13 C as a proxy for long-term WUE. Leaf δ 13 C correlated positively with iWUE across species in both juvenile and mature trees, while GCL showed a negative and SD a positive effect on iWUE and leaf δ 13 C. Within species, however, only GCL was significantly associated with iWUE and leaf δ 13 C. SLA had a minor negative influence on iWUE and leaf δ 13 C, but this effect was inconsistent between juvenile and mature trees. We conclude that GCL and SD can be considered functional morphological traits related to the iWUE and leaf δ 13 C of trees, highlighting their potential for rapid phenotyping approaches in ecological studies., (© 2024 The Author(s). Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.)

Succulence is a trait that describes water storage in plant organs and tissues regardless of life form. Plants use the stored water to maintain physiological function and delay desiccation. However, it is unclear whether succulence in leaves, stems and roots of woody plants delays desiccation, whether it provides 'utilizable water' to maintain physiological function, or buffers changes in water status in drying soils through capacitance. We conducted a pot dry-down experiment with nine shrub species to determine whether woody plants with greater leaf, stem, or root succulence have greater shoot utilizable water or capacitance. We also investigated whether greater succulence delays desiccation, represented by cumulative VPD, until evapotranspiration ceased or until utilizable water was exhausted. Greater leaf and stem succulence were strongly related to greater shoot utilizable water and capacitance. However, desiccation time was not delayed in plants with greater total shoot succulence, utilizable water, or capacitance. Instead, woody plants with greater root succulence had longer desiccation times. This suggests that woody plants use aboveground succulence to maintain physiological function and water status during drought, whereas root succulence extends desiccation time. Our study improves the mechanistic understanding of how woody plants use stored water to survive in dryland ecosystems., (© 2024 Scandinavian Plant Physiology Society.)

Climate warming is projected to affect hydrological cycle in forest ecosystems and makes the forest-water relationship more controversial. Currently, planted forests are gaining more public attention due to their role in carbon sequestration and wood production relative to natural forests. However, little is known about how the global patterns and drivers of water yield and water-use efficiency (WUE) differ between planted and natural forests. Here, we conduct a global analysis to compare water yield and WUE in planted and natural forests using 946 observations from 112 published studies. The results showed that global average water yield coefficient was 0.29 for planted forests and 0.34 for natural forests. Planted forests exhibited lower water yield coefficient (p < 0.05) in three climatic regions (arid, dry subhumid, and humid regions), but higher (p < 0.01) WUE only in arid region, compared with natural forests. Both water yield coefficient and WUE in planted forests were significantly lower (p < 0.05) than that in natural forests for stand characteristic groups (stand density, average tree height, leaf area index [LAI], and basal area). Additionally, stand density within the ranging between 1000 to 2000 stem ha -1 can maximize the water yield and WUE in planted and natural forests. Water yield coefficient in planted forests was primarily controlled by the factors related to tree growth (i.e., tree height, DBH), while that of natural forest mainly affected by stand structure (i.e., LAI, stand density, DBH). WUE in planted forest was more sensitive to climate than in natural forests. This work highlights the critical role of natural forests in water supply and the importance of tree species selection and stand management (e.g., stand density adjustment) in plantations in future forest restoration policies and climate change mitigation., (© 2024 John Wiley & Sons Ltd.)

Rice growth and yield response to salinity can be influenced by the duration and the timing of salt stress. The present study tested the effects of saline water irrigation from vegetative growth to maturity on rice growth and yield and ion concentrations in the straw and root and related them to changes in soil salinity and soil solute potential. The treatments consisted of five levels of saline water irrigation (electrical conductivity ~0.25 (control), 4, 6, 8, and 10 dS m-1) with two rice cultivars (BRRI dhan67 and BRRI dhan99) grown in pots in a rain shelter. Grain weight per pot, dry straw weight, and root weight were significantly reduced with increasing water salinity, but BRRI dhan99 was less affected. With prolonged saline water irrigation, salt concentration increased in the soil and lowered the soil solute potential. Increased saline water induced higher concentrations of Na+ in the straw (527-1200 mmol kg-1 at 4-10 dS m-1) relative to the root. By contrast, higher Cl- concentrations accumulated in the root than in the straw. The decrease of K+ in the straw and root for increasing salinity was inconsistent, but the Na+/K+ ratio sharply increased in the straw with higher water salinity. The increased Na+/K+ explained most grain weight loss due to higher salinity (R2 = 0.93) followed by Na+ (R2 = 0.87) and Cl-1 (R2 = 0.53). We conclude that the prolonged saline water irrigation has a cumulative effect on root zone salinity and solute potential that depresses grain yield in rice by increasing the Na+/K+ ratio in plants., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

When plants are transferred from nursery to urban environments, they often face drought stress due to inadequate maintenance, such as insufficient irrigation. Using drought tolerant species may help mitigate the adverse impact of drought stress in urban settings. Additionally, utilizing novel technologies for water status monitoring may help optimize irrigation schedules to prevent transplanting failures. This study investigated the physiological and biochemical responses of two ornamental shrubs, Photinia x fraseri and Viburnum tinus, subjected to water stress of increasing severity and rewatering. Water relations, gas exchanges, chlorophyll fluorescence and biochemical analyses were conducted alongside real-time monitoring of water status using leaf-water-meter sensors (LWM). The progression of water stress had a notable negative impact on leaf gas exchanges and water relations in both species. Notably, P. fraseri avoided photoinhibition by reducing chlorophyll content and actual efficiency of PSII. Adjustments in leaf phenolic compounds played a significant role in enhancing drought tolerance of both species due to their antioxidant and photoprotective properties. Upon rewatering, both species exhibited complete recovery in their physiological functions, underscoring their remarkable tolerance and resilience to drought stress. Additionally, LWM sensors efficiently tracked the dehydration levels, exhibiting a rising trend during the water stress progression and a subsequent decline after rewatering for both species. These findings confirm the reliability of LWM sensors in monitoring physiological status of plants in outdoor contexts, making them a suitable tool for use in urban settings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

In this study, an atmospheric pressure air plasma jet (APAPJ) was employed to generate plasma-activated water (PAW), which was applied to treat maize (monocot) and pea (dicot) seeds for evaluating its influence. This research explored APAPJ diagnostics by varying the air feed rate as 1, 2, and 3 liter per minute (Lpm) through current-voltage characterization, optical emission spectroscopy, electron temperature and density, nitrogen metastable state density, and rotational and vibrational temperature of the plasma. Additionally, various reactive oxygen and nitrogen species (RONS) formed and physicochemical properties of PAW were analyzed by varying plasma treatment time from 0 to 8 min. Furthermore, the water uptake of maize (Zea mays) and pea (Pisum sativum) seeds were examined by the measurement of the contact angle. Results indicated that APAPJ has the capacity of fostering germination, growth, chlorophyll, phosphorus, nitrite, nitrate, ammonium ion and leaf area in plants significantly with an optimized 6 min treated PAW for maize and 2 min treated PAW for peas. Among various categories, seeds soaked in PAW and irrigated with PAW exhibited the most outstanding result in germination and plant growth. Non-thermal plasma showed promising green methods for enhancing plant growth and boosting nutrient content., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Water use efficiency (WUE) represents the trade-off between carbon assimilation and water loss in plants. It remains unclear how leaf stomatal and photosynthetic traits regulate the spatial variation of leaf WUE in different natural forest ecosystems. We investigated 43 broad-leaf tree species spanning from cold-temperate to tropical forests in China. We quantified leaf WUE using leaf δ 13 C and measured stomatal traits, photosynthetic traits as well as maximum stomatal conductance ( G w max ) and maximum carboxylation capacity ( V c max ). We found that leaves in cold-temperate forests displayed 'fast' carbon economics, characterized by higher leaf nitrogen, Chl, specific leaf area, and V c max , as an adaptation to the shorter growing season. However, these leaves exhibited 'slow' hydraulic traits, with larger but fewer stomata and similar G w max , resulting in higher leaf WUE. By contrast, leaves in tropical forests had smaller and denser stomata, enabling swift response to heterogeneous light conditions. However, this stomatal configuration increased potential water loss, and coupled with their low photosynthetic capacity, led to lower WUE. Our findings contribute to understanding how plant photosynthetic and stomatal traits regulate carbon-water trade-offs across climatic gradients, advancing our ability to predict the impacts of climate changes on forest carbon and water cycles., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

Human carbonic anhydrases (hCAs) have essential roles in respiration, acid-base balance, and fluid secretion, with implications in diseases such as glaucoma, epilepsy, obesity, and cancer. Of the fifteen known hCAs, human CA I (hCA I) is particularly abundant in erythrocytes, playing a critical role in CO 2 transport. Despite extensive research on hCA I, the impact of post-translational modifications (PTMs), particularly phosphorylation, on its catalytic activity and inhibitor binding remains poorly understood. Although multiple phosphorylation sites have been identified in hCA I in vivo through high-throughput proteomics studies including at the highly conserved Ser51 residue, the functional consequences of these modifications are not well characterized. We investigated the effects of a phosphomimetic mutation at Ser51 on hCA I, examining its catalytic efficiency and susceptibility to inhibition by sulfonamides and anions. Using a recombinant expression system and a stopped-flow kinetic assay, we characterized the CO 2 hydration activity and inhibition profiles of S51E hCA I compared to the wild type enzyme. Our results demonstrate that the S51E mutation increases the catalytic turnover rate (k cat ) from 2.0 × 10 5 s -1 to 2.6 × 10 5 s -1 but significantly decreases substrate affinity, raising the Michaelis constant (K M ) from 4.0 mM to 13.9 mM, reducing overall catalytic efficiency by over 50 %. Inhibition studies with a panel of 41 sulfonamides revealed that the S51E mutation dramatically alters inhibitor sensitivity, particularly for the most effective inhibitors. For example, 15 of the 16 most effective sulfonamide inhibitors for hCA I (with K I s <350 nM) were an average of over 35-fold less effective in inhibiting S51E hCA I than the wild type. The K I of the anticonvulsant zonisamide increased from 31 nM for the wild type hCA I to 4.0 μM. The inhibition profile with a panel of 37 small anions further indicated that the S51E mutant exhibited significantly reduced susceptibility to inhibition by 24 out of 37 tested anions, with some K I values increasing by up to 11,000-fold for inhibitors like hydrogen sulfide. This study underscores the significant impact that phosphorylation may have on hCA I function and inhibition. By characterizing the effects of phosphorylation on the CO 2 hydration activity and inhibitor sensitivity of hCA I, these findings represent early steps in developing more selective proteoform-specific inhibitors, which could lead to more effective treatments for diseases involving carbonic anhydrases., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Understanding the relationship between wind speed and gas exchange in plants is a longstanding challenge. Our aim was to investigate the impact of wind speed on maximum rates of gas exchange and the kinetics of stomatal responses. We conducted experiments in different angiosperm and fern species using an infrared gas analyzer equipped with a controlled leaf fan, enabling precise control of the boundary layer conductance. We first showed that the chamber was adequately mixed even at extremely low wind speed (<0.005 m s -1 ) and evaluated the link between fan speed, wind speed, and boundary layer conductance. We observed that higher wind speeds led to increased gas exchange of both water vapor and CO₂, primarily due to the increase in boundary layer conductance. This increase in transpiration subsequently reduced epidermal pressure, leading to stomatal opening. We documented that stomatal opening in response to light was 2.5 times faster at a wind speed of 2 m s -1 compared to minimal wind speed in Vicia faba, while epidermal peels in a buffer with no transpiration exhibited a similar opening rate. The increase in stomatal conductance under high wind was also observed in four angiosperm species under field conditions, but it was not observed in Boston fern (Nephrolepis exaltata), which lacks epidermal mechanical advantage. Our findings highlight the significant impact of boundary layer conductance on determining gas exchange rates and the kinetics of gas exchange responses to environmental changes., (© 2024 The Author(s). The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Silica nanoparticles (SiNPs) and brassinolide (BR) have been used as nano-fertilizer and growth regulator, respectively to enhance crop tolerance to abiotic stress. However, it is unclear whether a combination of the two (BR + SiNPs) is more beneficial than single application of BR or SiNPs to improve the growth of deficit-irrigated sugar beets. In this study, a two-year (2022-2023) field experiment was conducted to investigate the effects of foliar spraying of water (CK), SiNPs, BR, and BR + SiNPs on the antioxidant defense, photosynthetic capacity, dry matter accumulation, nutrient uptake, and yield of sugar beets under full irrigation (100% of crop evapotranspiration (ETc), W1) and deficit irrigation (60% ETc, W2). The results showed that compared with the application of BR or SiNPs, the application of BR + SiNPs could enhance the antioxidant defense, osmoregulation, and photosynthesis of the full-irrigated and deficit-irrigated sugar beet leaves, and ultimately improved the water status, growth, and yield of sugar beet plants. There was no significant difference in the net revenue (NR) between BR + SiNPs treatment and CK under W1 conditions. However, the NR of the BR + SiNPs treatment increased by 27.0% (p < 0.05) compared with that of CK under W2 conditions, and there was no significant difference in NR between BR + SiNPs and SiNPs treatments. A comprehensive evaluation using entropy weight combined with technique for order preference by similarity to ideal solution method found that under deficit irrigation condition, spraying SiNPs could improve the growth of sugar beet, increase the TY, NR, and water use efficiency, and reduce costs compared with spraying BR + SiNPs. Therefore, foliar spraying of SiNP on deficit-irrigated sugar beets can be used to improve sugar beet growth and reduce the potential economic losses caused by deficit irrigation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Waterlogging stress negatively affects plant growth and survival. However, the ability of Zanthoxylum armatum, a valuable tree species, to tolerate and adapt to waterlogging stress remains poorly understood. Here we report how alcohol dehydrogenase 1 (ZaADH1) confers waterlogging stress tolerance in Z. armatum. ZaADH1 expression was induced after waterlogging treatment. ZaADH1 overexpression increased waterlogging stress by modulating the metabolite levels of the ADH enzyme, soluble sugar, and trehalose, promoting glycolysis and carbohydrate metabolism. The overexpression of ZaADH1 in Arabidopsis thaliana increased the total plant area and chlorophyll content, thereby increasing resistance to waterlogging stress. Physiological and overexpression transcriptome analyses in A. thaliana indicated that ZaADH1 overexpressing lines generated more carbohydrates to meet energy demands, employing a "static" strategy to increase tolerance to waterlogging stress, which confirms the conservation of the ADH1 response to waterlogging stress and represents a potential crucial measure for improving waterlogging tolerance in Z. armatum., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Masson SAS.)

Ongoing climate changes are expected to intensify drought periods in tropical regions, directly impacting epiphytic bromeliads that depend on intermittent water availability. This study aimed to elucidate if Acanthostachys pitcairnioides, an epiphytic bromeliad of Atlantic Forest, tolerates extended drought periods and the potential strategies involved in its tolerance and recovery capacity. We suppressed irrigation for 42 days, rehydrated plants for four days, and evaluated leaf water status, and photochemical, metabolic, and anatomical changes. During the initial 28 days of drought, translocation of water from hydrenchyma to chlorenchyma, higher chlorophyll content, and accumulation of abscisic and salicylic acid and antioxidants contributed to maintaining the cell turgor and functionality of photosynthetic apparatus. At 42 days, a significant reduction in leaf water content to 45.5% was accompanied by a 2.5-fold increase in non-photochemical quenching and enhanced levels of carotenoids, anthocyanins, osmoregulators (proline, myo-inositol, and trehalose), and phytohormones (abscisic acid and jasmonates). After rewatering, water storage in the hydrenchyma and almost all pigments, hormones, and metabolites were restored to pre-stress conditions. Leaf succulence, carbohydrate and organic acid accumulation, and carbon isotope data (δ 13 C-14.5‰) provide evidence of induction of CAM metabolism by water limitation in A. pitcairnioides. Our findings indicate the prevalence of water accumulation strategy during the first half of the drought stress. At the end of the drought period, the complete depletion of water from the hydrenchyma favored the osmotic adjustment. Considering this set of tolerance strategies and the rapid recovery after rehydration, A. pitcairnioides can successfully withstand environments with restricted water availability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Skeletal muscle tissue is in a constant state of turnover, with muscle tissue protein synthesis and breakdown rates ranging between 1% and 2% across the day in vivo in humans. Muscle tissue remodeling is largely controlled by the up- and down-regulation of muscle tissue protein synthesis rates. Research studies generally apply stable isotope-labeled amino acids to assess muscle protein synthesis rates in vivo in humans. Following labeled amino acid administration in a laboratory setting, muscle tissue samples are collected over several hours to assess the incorporation rate of these labeled amino acids in muscle tissue protein. To allow quantification of bulk muscle protein synthesis rates over more prolonged periods, the use of deuterated water methodology has regained much interest. Ingestion of daily boluses of deuterium oxide results in 2 H enrichment of the body water pool. The available 2 H-atoms become incorporated into endogenously synthesized alanine primarily through transamination of pyruvate in the liver. With 2 H-alanine widely available to all tissues, it becomes incorporated into de novo synthesized tissue proteins. Assessing the increase in tissue protein-bound 2 H-alanine enrichment in muscle biopsy samples over time allows for the calculation of muscle protein synthesis rates over several days or even weeks. As the deuterated water method allows for the assessment of muscle tissue protein synthesis rates under free-living conditions in nonlaboratory settings, there is an increasing interest in its application. This manuscript describes the theoretical background of the deuterated water method and offers a comprehensive tutorial to correctly apply the method to determine bulk muscle protein synthesis rates in vivo in humans., Competing Interests: Conflict of interest The authors report no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

With global climate change, the frequent occurrence of intense rainfall and aggravation of waterlogging disasters have severely threatened the plant growth and fruit quality of grapevines, which are commercially important fruit crops worldwide. There is accordingly an imperative to clarify the responses of grapevine to waterlogging and to propose appropriate remedial measures. Strigolactone (SL) is a phytohormone associated with plant abiotic stress tolerance, while, its function in plant responses to waterlogging stress remain undetermined. In this study, systematic analyses of the morphology, physiology, and transcriptome changes in grapevine leaves and roots under post-waterlogging and GR24 (a synthetic analog of SL) treatments were performed. Morphological and physiological changes in grapevines in response to post-waterlogging stress, including leaf wilting and yellowing, leaf senescence, photosynthesis inhibition, and increased anti-oxidative systems, could be alleviated by the application of GR24. Moreover, transcriptome analysis revealed that the primary gene functions induced by post-waterlogging stress changed over time; however, they were consistently associated with carbohydrate metabolism. The GR24-induced leaf genes were closely associated with carbohydrate metabolism, photosynthesis, antioxidant systems, and hormone signal transduction, which were considered vital aspects that were influenced by GR24 in grapevine to induce post-waterlogging tolerance. Concerning the roots, an enhancement of microtubules and cytoskeleton for cell construction in GR24 application was proposed to facilitate root system recovery after waterlogging. With this study, we comprehend the knowledge regarding the responses of grapevines to post-waterlogging and the ameliorative effect of GR24 with the insight to the transcriptome changes during these processes., Competing Interests: Declaration of competing interest The authors affirm no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Waterlogging stress is a severe abiotic challenge that impedes plant growth and development. Ramie (Boehmeria nivea L.) is a Chinese traditional characteristic economic crop, valued for its fibers and by-products. To investigate the waterlogging tolerance of ramie and provide the scientific basis for selecting waterlogging-tolerant ramie varieties, this study examined the morphological, physiological, biochemical, and molecular responses of 15 ramie germplasms (varieties) under waterlogging stress. The results revealed varied impacts of waterlogging stress across the 15 ramie varieties, characterized by a decrease in SPAD values, net photosynthesis rates, and relative water content of ramie leaves, along with a significant increase in relative conductivity and the activities of antioxidant enzymes such as SOD, POD, CAT, and APX. Additionally, the levels of soluble sugars, soluble proteins, and free proline exhibited varying degrees of increase. Through Principal Component Analysis (PCA), ZZ&#95;2 and ZSZ&#95;1 were identified as relatively tolerant and susceptible varieties. Transcriptome analysis showed that the differential expressed genes between ZZ&#95;2 and ZSZ&#95;1 were significantly enriched in metabolic pathways, ascorbate and aldarate metabolism, and inositol phosphate metabolism, under waterlogging stress. In addition, the expression of hypoxia-responsive genes was higher in ZZ&#95;2 than in ZSZ&#95;1 under waterlogging stress. These differences might account for the varied waterlogging responses between the two varieties. Therefore, this study explored the morpho-physiological responses of ramie under waterlogging stress and identified the molecular mechanisms involved, providing valuable insights for improving ramie varieties and breeding new ones., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Contradictory evidence exists regarding the relevance of Péclet-like gradients in leaf water isotopes, making it difficult to accurately predict variation in isotope composition. Here, we use H 2 18 O vapour labelling to directly test whether leaf water isotopes diffuse back into the xylem to be carried forward to more distal leaf portions. Backward diffusion has been assumed, due to observations of increasing enrichment towards the tip and outer edges of some leaves. Further complicating the selection of leaf water isotope models is the observation that some, but not all, leaves demonstrate a radial Péclet effect in bulk leaf water and that the hydraulic design of leaves may influence the development of isotope gradients in leaves. Carry-forward of H 2 18 O vapour label was detected in the two monocot species assessed (oat and corn), but not in the two dicot species (foxglove and sunflower). Further, bulk leaf water measurements at differing transpiration rates indicated that a bulk leaf water Péclet effect was relevant for foxglove only. We conclude that both leaf hydraulic design and relative velocities of water within transport pathways influence leaf water isotope composition, reconciling seemingly contradictory previous results regarding the relevance of Péclet effects to leaf water isotopes., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)